A series of established mouse cell lines which ahve acquired a transformed, tumor-like, phenotype following exposure to chemical carcinogens have been found to behave in a fashion consistent with "dominant" expression of the transformed phenotype. High molecular weight DNA from viral and chemical transformants has been successfully used to transfer anchorage independence to untransformed mouse (NIH/3T3). We propose to charaterize the genetic basis by isolation of the gene (Tf+) and its normal countepart using gene transfer and recombinant DNA techniques.